Cerebrospinal fluid (CSF) space enlargement in schizophrenia is a prominent finding. This study was initiated to examine the influence of genetic loading, obstetric complications and premorbid adjustment on the extent of this enlargement. The sample of this MRI study consisted of 40 schizophrenic patients, 24 psychiatric and 40 healthy family members from 10 uniaffected and 19 multiple affected families with schizophrenia, such as 27 control subjects from non-affected families. The ventricle-to-brain-ratio (VBR), and the areas of the third ventricle, sylvian fissure, temporal horn and interhemispheric fissure at the slice where these structures reached their maximum were examined relatively to the corresponding total brain areas. The sum of CSF areas was calculated as a parameter for global atrophy. From MANCOVA adjusted for intervening variables the right VBR and the sum of CSF areas revealed significant differences between diagnostic groups. For these areas schizophrenic patients showed an increase compared to control subjects and family members with psychiatric disorder. Genetic loading influenced the interhemispheric fissure, enlarged in multiple affected compared to uniaffected families, and the temporal horn asymmetry, which was right sided (right > left) in control subjects and multiple affected families, but inverted in uniaffected families. Neonatal obstetric complications influenced only the size of the VBR, while premorbid adjustment predicted various CSF areas. In conclusion, schizophrenic subjects from multiple and uniaffected families showed a global atrophy, which was most pronounced in the VBR. Genetic loading seems to have an impact on frontal regions as the interhemispheric fissure and on the temporal horn.